Boston just had a preliminary election yesterday (more or less what other places call a primary, though it’s non-partisan). As you know from my post of September 22, one of the topics that I teach in my Quantitative Reasoning class is Boston’s variant of the two-round runoff system.

First of all, you need to know the structure, which was designed to assure that winners are supported by the majority of voters, not just pluralities. Let’s take a made-up example to illustrate the method. Suppose we have five candidates for mayor: Anderson, Baker, Castro, Duval, and Esposito. Anderson is a conservative, the rest are liberals. In the preliminary election, we get the following results:

Who wins? It depends on the math! In the First Past the Post system — the one we use in elections for Massachusetts governor, for example — Anderson would win, having the most votes. But clearly Anderson is not supported by anywhere close to a majority of the voters (less than 27%, in fact). In the Two-Round Runoff system or its Boston variant, we then hold a final election, in which only the top two vote-getters are on the ballot: Anderson and Baker in this case. Anderson picks up a few votes from those who supported the candidates who are no longer on the ballot (Castro, Duval, Esposito) and from those who hadn’t voted in the preliminary at all, but Baker gets the overwhelming fraction of Castro voters, Duval voters, and Esposito voters, with the following results:

Baker wins with the clear support of the majority. (There are certainly some flaws to this system, but it does ensure a mayor with majority support.)

So… what happened in yesterday’s preliminary election?

Well, as they say, it’s complicated. Here’s why: along with the usual number of mayors (one), Boston has 13 city councilors, of whom — wait for it! — 9 are elected in districts and 4 are elected city-wide (“at large”). Each district elects one councilor, so those seats are determined just like the mayor’s, but there are four city-wide councilors, so many get to be on the final ballot? The answer is that it’s always twice the number of open positions, so it’s 8 in this case. We had 15 candidates in the preliminary, of whom the top 8 survive to be on the ballot for the final. That actually makes mathematical sense, if you think about it.

Here are the (preliminary) results from the Dorchester Reporter:

This has got to be the most diverse group of at-large councilor finalists ever. The quotes in the Reporter drive home the point:

“I am anxiously optimistic about our finish tonight,” Essaibi-George told the Reporter. “I think that we obviously have quote unquote ‘won’ in this preliminary and we’ll make it to the next round…. For me this is a momentary celebration and the work continues tomorrow morning.”

“Honestly, I think there were a few people that would have liked to see me beat today,” she added. “I think it’s because I’ve demonstrated a commitment to honesty, a commitment to transparency, a commitment to action, a commitment to not just engaging with the voters and representing them vocally and in a very active way, but in a very honest way. I don’t paint a pretty picture. I can put on a fancy dress, but the work is hardcore, the work can be gritty, and as a Dorchester girl, I’m pretty okay with the gritty, and happy to show up at work every single day, and I do that very proudly and happily and without any bashfulness.”

Garrison, who finished fifth in the last city election and thus secured a council seat when now-US Rep. Ayanna Pressley left last January finished sixth in the balloting yesterday. Garrison’s “fourth seat” has been a target for new challengers in the field in this election— and on Tuesday it was Alejandra St. Guillen who claimed the slot.

“I am shocked and thrilled by this result, which I owe to the hard work of our amazing team of volunteers and supporters,” St. Guillen said in a statement released by her campaign. “I ran inspired by Ayanna Pressley, and other women of color who opened the path for candidates like myself. I hope to show our diverse residents that an LGBTQ Latina candidate can have a chance to represent the city of Boston. But there is still much work to do, we have a short time, and a long path to November 5, and can’t take our foot off the gas.”

Julia Mejia, who lives in Dorchester, was the fifth-place finisher— a result that thrilled the first-time candidate who moved to Boston as a child from the Dominican Republic.

“Today’s results are a clear message that the residents of Boston want real change. Voters want a Boston where all voices are part of the decision-making process in our city government, and elected officials in City Hall are held accountable,” Mejia said in a statement. “I’m proud of all the volunteers who are behind this campaign, and the many who are not typically involved in the political process or tied to a vast network of Boston’s political insiders.”

Dorchester’s Erin Murphy also punched her ticket to advance to the November finals with a seventh-place finish on Tuesday. She celebrated with family and supporters at the Industry in Adams Village.

“We crushed Dorchester and Southie,” Murphy said to the gathering. “Dorchester definitely put us over the top. I heard in City Hall they’re shocked by how [well] I did.”

“I’m feeling great! We’re still trying to get all the numbers in and see where we landed but overall. I think that Dorchester and our home-base really helped. We can only go up from here.”

“We’ve had no big help from other candidates,” she added. “I’ve been doing this all by myself and I’m going to keep working hard. I’m really looking forward to it,” Murphy said.

Categories: Dorchester/Boston, Math